The potential HP is primarily from the reduced mass allowing the motor to rev higher....but that is provided you have the airflow in your heads and cam for the motor to take advantage of it. Putting it another way, is valvetrain mass the main limiting factor now that's holding your combo back? Or is it airflow?

The Valvetrain itself doesn't give you very much within the original powerband RPM range....other than the reduction of mass, similar to the beneficial effects of a lighter bobweight. so providing proportionally higher head flow and cam is the key, so on a motor like yours raising the powerband to peak 500-600 rpm higher could easily be 70hp. The next question would be if your block can withstand the additional power and heat of the higher Peak torque RPM.